This invention relates to joint prosthesis, and more particularly to modular knee joint prostheses employed during knee arthroplasty procedures.
Knee arthroplasty is a well known surgical procedure by which a diseased and/or damaged natural knee joint is replaced by a prosthetic knee joint. Typical knee prostheses include a tibial component, a femoral component, and a patellar component. The femoral component generally includes a pair of spaced apart condylar portions, the superior surfaces of which articulate with a portion of the tibial component. A femoral stem assembly can also be used to provide lateral stability to the replaced knee joint. Femoral stem assemblies often include a stem member which seats within the medullary canal of a distal portion of a femur. The stem is typically coupled to the femoral component by a specialized collar and bolt.
Knee joint prostheses are available as modular assemblies to reduce the number of individual components that must be purchased and stocked, and to reduce the associated component handling time by the surgeon during arthroplasty procedures. An example of a prior art modular knee prosthesis is described in U.S. Pat. No. 5,152,796 (Slamin). The Slamin patent describes a modular knee prosthesis that includes a femoral component and a series of bolts that attach to and extend from the femoral component at different angles corresponding to different valgus angles. The valgus angle is defined as the angle between the center line of the femur and the vertical axis connecting the distal femur and the center of the femoral head, and is typically between 5.degree. and 9.degree.. The prosthesis also includes a plurality of femoral stems having different lengths and diameters.
Despite existing modular knee joint prostheses, there remains a need for a modular knee joint prosthesis that has sufficient versatility to accommodate differing patient anatomy and joint conditions. Many modem modular knee prostheses are characterized by a relatively excessive number of components with little or no part interchangeability. Such systems tend to increase purchasing costs because of part waste. Additionally, the excessive number of parts must be handled and stocked, thus increasing costs associated with inventory control and management.
It is thus an object of the invention to provide a modular knee prosthesis having sufficient versatility to accommodate different patient anatomy and joint conditions while maintaining a relatively low component count. It is another object of the invention to provide a modular knee prosthesis having components that are physiologically and geometrically compatible with different anatomical conditions. Still another object of the invention is to provide a modular knee prosthesis that is suitable for use in both right and left knee procedures. Other general and more specific objects of the invention will in part be apparent from the drawings and description which follow.